1. Field of the Invention
The present invention relates to a video reproduction apparatus including a multiplied speed driving function and a special reproduction function of a display unit, a video reproducing method, a program, and a recording medium thereof.
2. Description of the Related Art
Conventionally in a video reproduction apparatus such as a cathode-ray tube (CRT) type television, an impulse type display system which repeats flashing of light has been used. Therefore, a phenomenon hardly occurs, in which a preceding video remains as an image lag in a video that moves fast and the video looks blurred. In a video reproduction apparatus using a liquid crystal or the like, however, a backlight always lights, and a holding type display system is used. Therefore, a video looks blurred because a preceding video remains as an image lag.
In order to solve this problem, a video of 60 frames per second, for example, is converted into a video of 120 frames per second by inserting an interpolation frame which is generated from a preceding frame or from preceding and succeeding frames between the frames. Further, a video reproduction apparatus using a technique of two-fold speed driving for driving a display unit using a liquid crystal or the like at a speed that is twice a conventional speed to reduce a holding period of time by half and reduce an image lag feeling is in widespread use.
In Japanese Patent Application Laid-Open No. 2002-132224, for example, a liquid crystal display apparatus including a system for dividing one frame into two fields, displaying correction data in the first field and displaying data without any correction in the second field is discussed. On the other hand, a video reproduction apparatus using three-fold speed driving for further increasing a driving speed to reproduce 180 frames per second has also been known.
In a video reproduction apparatus, various special reproduction modes such as high-speed reproduction, skipped reproduction, and frame feeding reproduction have been executed for enabling a user to search for a scene to be viewed in a content. In an image reproduction apparatus described in Japanese Patent Application Laid-Open No. 8-98142, for example, a system for reproducing a content compressed and encoded in a Moving Picture Experts Group (MPEG) system at high speed is discussed. In an embodiment discussed in Japanese Patent Application Laid-Open No. 8-98142, processing for decoding a Bi-directionally predictive coded picture (B picture) is omitted to realize high-speed reproduction of the content.
As described above, the conventional video reproduction apparatus has the function of two-fold speed driving or three-fold speed driving of a display unit and a special reproduction function such as a high-speed reproduction function. In order to implement the functions in combination, frames are generated in the following procedure.
FIGS. 6A to 6C illustrates an outline of processing for frames at the time of three-fold speed reproduction in a conventional video reproduction apparatus. For compressed and encoded content data, frames B1, B2, I0, B4, B5, P3, B7, B8, P6, B10, B11, P9, B13, B14, and P12 are displayed in this order on a display unit 104 by way of example.
At the time of three-fold speed reproduction, a decoder is instructed to thin two frames out of every three frames and decode one frame. Therefore, the decoder decodes the frames I0, P3, P6, P9, and P12 in this order, as illustrated in FIGS. 6A to 6C.
When the display unit 104 is driven at a normal speed as illustrated in FIG. 6A, in other words, the display unit 104 is driven at the same driving speed to a frame rate of the input content, only a frame decoded by the decoder is displayed on the display unit 104. On the other hand, when the display unit 104 is driven at a two-fold driving speed as illustrated in FIG. 6C or a three-fold driving speed as illustrated in FIG. 6B, an interpolation frame to be inserted between the frames is generated from frame data for three-fold speed reproduction decoded by the decoder. Therefore, the frames for three-fold speed reproduction decoded by the decoder and the interpolation frames generated based on the frame data are displayed on the display unit.
However, an interpolation frame that is less needed may be generated according to a driving speed and a reproduction speed of the display unit.
In the example illustrated in FIG. 6B, for example, when the display unit 104 is driven at the three-fold driving speed, two interpolation frames are generated between the frame I0 and the frame P3. In original content data, however, the frame B4 and the frame B5 are not used as frames to be displayed at the time of three-fold speed reproduction, although they exist between the frame I0 and the frame P3. Therefore, interpolation frames are newly generated, although there are usable frames in an original image of the content, so that a processing load may be increased.
When the display unit is driven at a two-fold driving speed as illustrated in FIG. 6C, one interpolation frame is generated between the frame I0 and the frame P3. Conventionally, the interpolation frame is generated from the frame I0 and the frame P3 decoded for three-fold speed reproduction. However, in the original content data, the frame B4 and the frame B5 exist between the frame I0 and the frame P3. Therefore, an interpolation frame which can more accurately reproduce the original image on a time basis can be generated when it is generated using the frame B4 and the frame B5 than when it is generated using the frame I0 and the frame P3. Nevertheless, the interpolation frame is generated from the frame I0 and the frame P3 decoded for three-fold speed reproduction and used. Therefore, high-speed and accurate reproduction closer to the original image cannot be implemented.